UNIVERSITY  OF  CALIFORNIA  agricultural  experiment  Station 

COLLEGE   OF  AGRICULTURE  E-  J-  WiCKSON.  d. rector 

BERKELEY,   CALIFORNIA 


CIRCULAR   No.  73 

(October,  1911) 


PURE    INSECTICIDES 


BY 

C.  W.  WOODWORTH. 


Most  of  the  chemicals  used  as  insecticides  and  fungicides  are 
entirely  satisfactory  when  of  low  grade,  provided  the  approximate 
strength  is  known.  The  California  Insecticide  Law  permits  any  grade 
to  be  sold,  requiring  a  statement  of  its  composition  and  providing 
that  it  shall  not  be  lower  than  within  5  per  cent  of  the  percentage 
claimed  on  the  label. 

For  high  grade  goods  the  limit  of  variation  allowed  under  the  law 
is  too  great,  since  it  does  not  provide  a  means  of  fixing  a  minimum 
guarantee  above  95  per  cent,  and  then  only  when  labeling  them  100 
per  cent. 

Because  of  this  5  per  cent  variation  permitted  by  the  law  the  actual 
guarantee  is  below  the  label  guarantee  to  the  extent  of  the  amounts 
shown  in  the  following  table : 


Label  guarantee 

Actual  guarantee 

% 

% 

100 

95 

99 

94.05 

98 

93.1 

97 

92.15 

96 

91.2 

95 

90.25 

For  the  purpose  of  providing  for  the  more  accurate  specification 
of  high  grade  goods  the  following  plan  is  suggested : 

1st.  Use  the  term  "Pure"  without  the  designation  of  per  cent  for 
goods  that  do  not  fall  below  95  per  cent. 

2nd.  Use  the  form  "Guaranteed  not  less  than  96%"  for  goods 
that  Avill  not  fall  below  that  figure,  and  a  similar  form  for  still  higher 
grades. 


The  following  list  of  chemicals  and  crude  drugs  have  been  regis- 
tered under  the  percentages  indicated,  but  are  doubtless  in  most  cases 
of  high  enough  grade  to  justify  the  use  of  the  higher  forms  of  guar- 
antee suggested  above : 


Caustic  Soda   (NaOH),  98%. 
Hydrated  Lime   (Ca20H), 
Borax   (2B,03.  Na,0  +  10  H20), 

99.6%,  99%,  95-99%. 
Hellebore,  100%. 
Tobacco,  100%. 
Quassia,  100%. 
Sabadilla,  100%. 
Staphisagria,  100%. 
Carbolic  Acid   (C6H5OH),  96%,  95%. 
Cresylic  Acid   (C8H4OHCH„),  95-99%. 
Carbon  Tetrachlorid  (C  Cl4),  99.92%, 

99.7%,  97-99.9%. 
Bluestone   (CuS04  +  5H,0),  99.5%, 

99%,  98-99%,  97i/>-98%,  96.5%, 

95%. 
Copperas   (FsS04  +  7H,0),  98%, 

97%,  96%. 
Corrosive  Sublimate  (HgCL),  99.5%, 

99%,  98-99.9%. 


Sulphuric  Acid  (H2S04),  99.5%. 
Distillate  28°,  100%. 
Distillate  32°,  100%. 
Napthalene  (C10H8),  100%,  99%%, 

98%,  96.3%,  95-100%. 
Oil  Myrbane,  100%,  99%. 
Oil  Pennyroyal,  99%. 
Oil  Peppermint,  99%. 
Pyrethrum,  99%. 
Pyrethrum  flowers,  100%. 
Camphor,  98-100%. 
Permanganate  of  Potash  (KMn04), 

99%,  98%. 
Sodium  FJuorid  (NaF),  100%,  95%. 
Sulfur  (S),  99.7%,  99.5-100%,  99.5%, 

99-100%,  99%,  98-991/,%,  98-99%, 

98%,  97%,  95%. 
Carbon  Bisulfid   (CS,),  97-99.9%, 

97%. 


Dealers  who  wish  to  list  their  goods  in  accordance  with  these  sug- 
gestions will  be  permitted  to  amend  their  application  for  License 
without  further  cost  by  simply  filing  a  statement  at  the  Insecticide 
Laboratory. 

When  goods  are  guaranteed  "Pure,"  or  100  per  cent,  they  are 
considered  as  complying  with  the  law  if  they  do  not  fall  below  95 
per  cent.  Dealers  using  the  expression  "not  less  than"  thereby  ex- 
pressly waive  the  5  per  cent  variation  permitted  under  the  law  and 
become  liable  if  their  goods  do  not  come  strictly  up  to  their  guarantee. 
No  dealer  is  required  by  law  to  make  these  higher  guarantees,  but 
when  they  have  goods  which  they  can  safely  guarantee  higher  than 
the  law  requires  they  have  the  right  to  the  commercial  advantage  of 
their  superior  product,  hence  this  plan  for  a  voluntary  higher  guar- 
antee than  provided  by  the  Insecticide  Law. 


